Tape may be obsolete in the shallow end of the pool where you play.
Show me a production Petabyte-class data storage system that's entirely disk-based, with an exponential growth curve; then we can talk about obsolescence.
When you have data holdings that grow from 20TB to 1.5PB in 4 years,
(we do!) it's just not sane to do it any other way than tape. The cost of
media might be the same up front: the ongoing costs swing *way* toward
tape, for both environmentals and reliability.